SEPARATION AND PURIFICATION TECHNOLOGY
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2023
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IF 8.6
Nan Zhang,Yang Yang,Lijing Fan,Xiaoxu Zheng,Jinglin Wang,Cancan Jiang,Shengjun Xu,Hui Xu,Dongsheng Wang
Excessive discharge of fluoride can lead to environmental pollution and human hazards. Coagulation is a widely used process for the removal of fluoride. Existing research on the interaction between coagulants and fluoride has primarily concentrated on the removal of fluoride and the selection of coagulants, while studies on floc aging are lacking. Understanding the aging process of flocs can provide valuable insights into the mechanisms of interaction between coagulants and fluoride and further provide guidance for coagulation as well as sludge return processes. This study compares the fluoride removal efficiencies of two coagulants: polyaluminum-titanium chloride (PATC) and polyaluminum chloride (PACl), and examines the change patterns of fluoride ion during aging (0–120 h). Additionally, the study characterizes the impact of Ti or Al-Ti on the aging process using FTIR, XPS, XRD, and ESI-TOF-MS analyses. The results of the study demonstrate that the fluoride removal efficiency of PATC is 20.2% higher than that of PACl at a dosage of 0.8 mmol/L. The introduction of titanium provides additional binding sites for F − , resulting in a more intricate floc structure. Moreover, titanium promotes the hydrolytic polymerization of aluminum, increasing its positive charge and making it more attractive to F − . Upon the complete precipitation of the flocs, F − in the supernatant of PATC (0–6 h) and PACl (6–72 h) competes with -OH for binding sites, while F − attacks the Al-O or Al-O-Ti bond, leading to the disruption of the polymer. As time progresses, PATC flocs (6–120 h) are less affected by aging than PACl flocs (72–120 h). Throughout the aging process, PATC releases less F − at a slower rate, presumably because the introduction of titanium inhibited the dehydration and crystallization of the flocs to delay the release of F − .
研究领域:
环境科学
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化学工程
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产品关联
DOI
高影响因子
Journal of Environmental Sciences
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2019
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IF 3.556
Yuxiang Xue,Zhouzhou Liu,Aimin Li,Hu Yang
The applications of natural polymeric flocculants due to their green feature has been recently received much more attention. In this work, the combined usages of a cationic starch-based coagulant and polyaluminum chloride (PACl) were extensively evaluated for various addition sequences in the coagulation of both raw (surface water from the Jiuxiang River) and synthetic turbid water (two kaolin suspensions with different initial turbidities). Two typical cationic starch-based coagulants with different structures (St-G and St-E) were tried. In comparison to St-G, St-E and PACl used individually as well as St-G and St-E dosed after PACl, the combination of the starch-based coagulants fed before PACl showed higher turbidity removal efficiency, which featured not only less optimal doses of both inorganic and organic coagulants but also lower residual turbidity. On the basis of a detailed analysis of the particle size and its distribution in solution supernatants before and after coagulation by two starch-based coagulants and PACl, polymeric coagulants preferentially coagulate the small-sized colloids due to their distinct long-chain structures, but PACl preferentially coagulates the medium-sized ones. Thus, the medium-sized particles that were previously formed by the starch-based coagulants would be collectively and effectively removed by the subsequent addition of PACl. The addition sequence of the inorganic and organic coagulants in their combined usage is an important factor for improvement of the turbidity removal efficiency in practice.
研究领域:
环境科学
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水处理工程
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DOI
PubMed
高影响因子
CHEMICAL ENGINEERING SCIENCE
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2025
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IF 4.3
Yunxiao Ban,Zhijie Wan,Cong Ma,Yuzhen Wu,Haoran Chen
This study proposes a magnetic levitation fixed bed flocculation reactor as an effective method for the removal of Cr (VI). The research examines the effects of both single and dual polymer flocculants on the efficiency of the flocculation process. Initially, a magnetic levitation layer was established using a radial magnetic field in conjunction with stainless steel balls. Subsequently, polyaluminum chloride (PAC) and a non-ionic coagulant, polyacrylamide (NPAM), were introduced into the water to create a magnetic levitation fixed bed flocculation reactor. This reactor with the objective of purifying water contaminated with simulated Cr (VI). The results indicate that the incorporation of a reducing agent, specifically FeSO 4 , in conjunction with PAC and NPAM respectively, can achieve Cr (VI) removal rates exceeding 97% and turbidity removal rates exceeding 96%. The interaction between the cross-flow influent and the flocculating particles promotes the formation of micro-vortex flocculation.
研究领域:
环境科学
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水处理工程
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产品关联
DOI
高影响因子
CHEMOSPHERE
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2019
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IF 5.108
Kangying Guo,Baoyu Gao,Xiangwei Tian,Qinyan Yue,Ping Zhang,Xue Shen,Xing Xu
In this study, a series of polyaluminium chloride/papermaking sludge-based organic polymer (PAC-PSBF) composites with different PAC basicity and PAC/PSBF mass ratios were prepared from papermaking sludge . The basic properties of the aforementioned composites were characterized, and their flocculation efficiencies were studied in the disperse yellow (DY) and reactive blue (RB) dye removals. The results of the flocculation experiments demonstrated that PAC-PSBF composites performed better than PAC regardless of the PAC basicity or PAC/PSBF mass ratios. The composites with low PAC basicity were effective in DY and RB dye removals. PAC-PSBF composites with the same PAC basicity but higher PAC/PSBF mass ratios exerted more satisfactory color removals and floc properties in both DY and RB dye removals. PAC-PSBF composites were more pH-independent than PAC, and the excellent flocculation efficiencies of the composites was achieved at pH 4.0 to 8.0 in DY/RB dye removals. In brief, desirable flocculation efficiencies of the PAC-PSBF composites were obtained when PAC and PSBF were appropriately combined together.
研究领域:
环境科学
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化学工程
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产品关联
DOI
PubMed
高影响因子
JOURNAL OF ENVIRONMENTAL MANAGEMENT
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2024
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IF 8
Zhiyong Zhang,Chunxiao Liu,Boda Ouyang,Ming-Lai Fu,Lei Xu,Huachun Lan,Baoling Yuan
In this research, the effects of peracetic acid (PAA), polymeric flocculants, and their combined conditioning on improving the dewatering performance were comprehensively evaluated. The results showed that sludge cake moisture content, capillary suction time (CST), and specific resistance to filtration (SRF) were 70.6%, 48.1 s, and 3.42 × 10 12 m/kg after adding 0.10 g/gMLSS PAA for 50 min, representing reductions of 12.60%, 40.32%, and 33.98%, respectively. Additionally, conditioning of sludge with polyferric sulfate (PFS), polyaluminum chloride (PAC), and cationic polyacrylamide (CPAM) enhanced sludge properties in the following order: CPAM > PAC > PFS. After the PAA oxidation and re-flocculation process, the optimal dosages of PFS, PAC, and CPAM were reduced to 1.5 g/L, 0.9 g/L, and 0.04 g/L, respectively. The sludge dewatering performance significantly improved, with sludge cake moisture content measuring 65.8%, 66.3%, and 61.7%, respectively. Moreover, the spatial multi-porous skeleton structures were formed via re-flocculation to improve the sludge dewatering. Furthermore, economic evaluation validated that the pre-oxidation and re-flocculation process could be considered an economically viable option. These research findings could serve as a valuable reference for practical engineering applications.
研究领域:
环境工程
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污水处理
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产品关联
DOI
PubMed
高影响因子
ENVIRONMENTAL RESEARCH
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2024
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IF 7.7
Chang-An Huan,Qiandi Wang,Xiqi Li,Cong Du,Qingjie Meng,Xu Kang,Wenzong Liu
A huge production of waste activated sludge (WAS) has been a burden for wastewater treatment plants (WWTPs) with high disposal cost and little benefit back to wastewater purification. The short-chain fatty acids (SCFAs) produced by a short-term acidogenic fermentation of WAS before methane production have been proven to be a high-quality carbon source available for microbial denitrification process. The dual purpose of full recovery of fermentation liquid products and facilitating disposal of residual solid waste necessitate an efficient solid-liquid separation process of short-term fermentation liquid. The transformation and loss of various soluble carbon sources between solid and liquid are very important issues for carbon recovery efficiency when combining short-term fermentation and sludge dewatering in WWTPs. Here we testified the three conventional preconditioning coagulants, Polyferric Sulfate (PFS), Poly Aluminum Chloride (PAC) and Polyacrylamide (PAM), to improve the efficiency of subsequent solid-liquid separation. The results show that conversion yield of SCFAs in the liquid phase of sludge after short-term fermentation was 195 mg COD/g VSS, when using the coagulants PFS, PAC, and PAM for recovery, the recovery ratio was 79.5%, 82.0%, and 85.9%, respectively, while the dewaterability could be improved after preconditioning short-term fermentation sludge. The complexation of Al 3+ /Fe 3+ in metal coagulants with carboxyl groups of SCFA demonstrated by Density Functional Theory calculation led to small part of soluble carbons co-migration to the solid phase, mainly a loss of high molecular weight organic compounds (carbohydrate, proteins, humic acids), while the application of PAM had little impact on carbon recovery. Economic calculations further showed PAM preconditioning short-term fermentation liquid of WAS could achieve higher recovery benefits.
研究领域:
环境工程
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污水处理
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生物技术
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DOI
高影响因子
CHEMOSPHERE
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2024
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IF 8.1
Mengxin Yu,Yu Qian,Maofei Ni,Zhikang Wang,Ping Zhang
In this study, we examined the modulation of algae removal and algal organic matter (AOM) chemistry by potassium permanganate and poly-aluminum chloride (KMnO 4 -PAC) in simulated karst water. Specifically, we verified the compositional changes of AOM sourcing from Chlorella sp. and Pseudanabaena sp. in response to the presence of divalent ions (Ca 2+ and Mg 2+ ). Aromatic protein and soluble microbial products were identified as the primary AOM components. Divalent ions accelerated dissolved organic carbon (DOC) and UV 254 removal, particularly with Pseudanabaena sp. greater than Chlorella sp. (P < 0.05). Surface morphology analysis manifested that the removal of filamentous Pseudanabaena sp. was more feasible in comparison to globular Chlorella sp.. Our results highlight the significance of divalent ions in governing chemical behaviors and subsequent removal of both algae and AOM. This study upscales the understanding of the interactions among divalent ions, algae and AOM during preoxidation and coagulation process in algae-laden karst water.
研究领域:
环境科学
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水处理
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化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）